The quote "Guilt is a self-indulgence" from Marian Keyes' book "Lucy Sullivan Is Getting Married" suggests that feeling guilty can often serve as a form of self-centeredness. Rather than being productive or helping the situation, guilt may keep individuals fixated on their own feelings rather than seeking resolution or understanding. This perspective invites readers to reconsider how their emotions impact their actions and relationships.

In the context of the narrative, this insight into guilt reflects a broader theme of personal growth and self-acceptance. The characters grapple with their past actions and the weight of their choices, highlighting the importance of moving forward instead of being trapped by regret. Keyes' work ultimately encourages embracing one's journey without the burden of guilt, promoting a healthier mindset.